When Voyager I—which recently became the first manmade object to reach interstellar space—flew by Jupiter's moon Io back in 1979, the satellite's two-camera Imaging Science System squinted at the molten, pockmarked world and took as many photos as it could before it zoomed by.

These primitive black-and-white photos were then beamed to earth via radio wave using Voyager's 12-foot dish antenna, where NASA scientists squinted at them on primitive computers. But in 1979, there was no Adobe, no Photoshop. So to put together a complete picture of Io, NASA had to do it the old-fashioned way: They had to print out all the images, then cut them apart and paste them together by hand.

The fantastic image above is a look at the process of putting the jigsaw of an entire moon together. Using a massive board, NASA scientists took each Voyager photograph and carefully positioned it, overlapping photos as necessary to create a complete picture of Io. It was painstaking work, but it revealed a moon (and indeed, a world) unlike any other we had encountered before.

Io was not a dead, dusty moon like our own. On Io, massive volcanoes ruptured with lava, and massive plains gave way to enormous mountains higher than Mount Everest. Volcanic plumes and lava flows result in a surface that is seething in shades of yellow, red, white, black, and even green. The surface of Io was that of an apocalyptic world on fire, and the Voyager collage seen above was our first real view of it.

Of course, by the time Galileo followed up the Voyager 1 flyby in the 1990s, things were done very differently. Photoshop had finally made stitching together an alien world by hand a thing of the past.

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